Onthophagus comperei

Beneficial

Common name(s)

Compere's dung beetle

Taxonomy

Family: Scarabaeidae Subfamily: Scarabaeinae Genus: Onthophagus Species: Onthophagus comperei Blackburn, 1903

Adult diagnosis

Total body length 7.0–9.0 mm (0.27–0.35 in). Body shape oval; may be caked in dung. Color shiny black. Small to medium-sized Onthophagus, over 6 mm. Clypeal apex of major male produced and strongly recurved; not produced or recurved in minor male and female. Head of major male with 2 sinuate, vertically-oriented horns, apex of horns weakly bifurcate, no ridge between horns, horns variable in size; minor male and female with 2 tubercles near base of head. Ocular canthus not completely dividing eye. Pronotum with anterior angles curved weakly outward; surface lacking distinct process in either sex. Front tibia of male somewhat slender, female tibia comparatively more stout. Scutellum absent.

Larval diagnosis

Undescribed. For Onthophagus spp. (Ritcher, 1966): Grub C-shaped, hump-backed, cylindrical, and cream-colored. Maxilla with galea and lacinia distinctly separate. Epipharynx with tormae united mesally, anterior phoba present. Antennae 4-segmented, distal segment much reduced. Legs 2-segmented. Prothoracic shield without anteriorly projecting processes. Third abdominal segment bearing a prominent conical, dorsal gibbosity covered with numerous short, stout setae.

Native range

Australia. This species is native to Queensland, Australia. It has been recorded from the Townsville area southward to the Stewart River (Matthews, 1972).

Plant host(s)

None. This species feeds on dung as both an adult and larva. There are no records of this beetle feeding on live plant tissues.

Life history

This nocturnal species is recorded from tropical savannahs and open woodlands (Matthews, 1972). Life history is poorly known, but related Onthophagus species are dung tunnelers, with females creating a burrow under or near dung (Woodruff, 1973). The burrow is then provisioned with dung in the form of brood balls. Each ball is impregnated with an egg; larval development occurs within the brood ball.

Pest potential

None. This species recycles dung and is beneficial for ranching and farming in Hawaii. Primarily being a dung feeder, this species has never been recorded damaging crop or ornamental plants. Additionally, this scarab is not a threat to native dung beetles because none occur in Hawaii or Guam.

Status in Hawaii

Recorded, not established. This species was intentionally brought to Hawaii in 1921, though it is appears no specimens were released (Hawaii Division of Forestry, 1923).

Status in Guam

Not established or recorded. There are no records of this species from Guam.

Potential distribution and dispersal pathway

In Hawaii, this species was intentionally imported.

Similar species

This scarab could be confused with other Onthophagus species of similar coloration and small to medium-size (more than 6 mm): Onthophagus binodis, Onthophagus incensus, Onthophagus armatus, Onthophagus cuniculus and Onthophagus laminatus.

Major males of these species can most readily be distinguished by examining the head armature (O. comperei with two sinuate, vertically-oriented, weakly bifurcate horns versus O. binodis lacking horns, O. cuniculus lacking horns but with paired tubercles at base of head, and O. incensus, O. armatus and O. laminatus with non-bifurcate horns).

Females are somewhat more difficult to distinguish, but can nonetheless be separated by examining the base of the head (O. comperei with two tubercles versus O. binodis and O. cuniculus with a slightly curved ridge, O. laminatus and O. incensus with a transverse ridge, and O. armatus with a feebly bisinuate ridge), the pronotal process (O. comperei female without a process versus O. binodis with a small lobe-like process, O. cuniculus with a bi-lobed process) and the pronotal anterior angles (O. comperei with the anterior angles rounded versus O. cuniculus and O. laminatus with the anterior angles curved outward).

Other names (synonyms)

None known

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Onthophagus comperei female; photo by E.L. Engasser

Onthophagus comperei female; photo by E.L. Engasser

Onthophagus comperei female; photo by E.L. Engasser

Onthophagus comperei female; photo by E.L. Engasser

Onthophagus comperei female; photo by E.L. Engasser

Onthophagus comperei female; photo by E.L. Engasser

Onthophagus comperei female; photo by E.L. Engasser

Onthophagus comperei female; photo by E.L. Engasser